const isLogin = true
function App () {
  return (
    <div className="App">
      {/* 逻辑与 && */}
      {isLogin && <span> this is sapn  </span>}
      {/* 三元运算符 */}
      {isLogin ? <span>JACK</span> : <span>Loading...</span>}
    </div>
  )
}

export default App
